The next step is to choose a cost estimation method that suits the project characteristics, available data, and level of accuracy required. Analogous estimation uses historical data and experience from similar past projects to estimate the cost of the current project. It is a quick and easy method, but it relies on the availability and quality of the data, as well as the similarity of the projects. Parametric estimation uses statistical models and equations to estimate the cost of the project based on one or more parameters. This method is more accurate and reliable, but it requires a large and valid data set, as well as a well-defined relationship between the parameters and the cost. Bottom-up estimation involves breaking down the project into smaller and more detailed components, such as tasks, subtasks, and resources, before estimating their cost individually. This is a more detailed and precise method, but it also requires more time and effort, along with more information about the project scope and activities. Three-point estimation uses three different estimates for each project component: the most optimistic, the most pessimistic, and the most likely. A formula such as PERT (Program Evaluation and Review Technique) is then applied to calculate the expected cost of the project based on these estimates. This is a more realistic and risk-adjusted method, however it also requires more data and analysis, as well as some degree of subjectivity.